Let's put aside the rather muddled issue of whether or not Grant is, as billed, an "iconic" actor - though surely Withnail and I alone earns him a little cred?

Regardless, far more interesting than Grant's ultimate reveal were the hours leading up to it, in which Who fans speculated as to which big-name stars would sign up for a role on the BBC's hit sci-fi drama.

An interesting debate began - who is 'too big' for Doctor Who? Is anyone really too starry for one of the biggest shows on UK television? The series has nabbed film stars and big US TV actors before, with more to come in the new series - Farscape's Ben Browder, acclaimed thespian Steven Berkoff...

But on the other hand, fans can get just a little carried away - Meryl Streep as the Rani was never gonna happen. This week's Tube Talk - Week in Geek takes a look at a few of the more popular names swirling round the rumor mill prior to the Grant announcement and asks... would they ever do a Who?

Patrick StewartAn iconic actor, most would agree - whether it's for his Shakespeare or his Star Trek performances, everyone loves Patrick Stewart. He's not adverse to doing TV - Extras, ITV's Eleventh Hour and voice work on American Dad are among his recent credits - and he's got form with both science fiction and a former Who star, having played Claudius to David Tennant's Hamlet.

We think Stewart would be the perfect big-name guest star for Doctor Who - he's both a recognizable face and a fantastic actor. We're sure he could be persuaded to take a trip aboard the TARDIS...

Surely for Mr Cumberbatch it's more a question of when he'll appear on Doctor Who rather than if? One could argue that a 'crossover' of sorts could muddy the brand of both Who and Sherlock - neither show exactly needs the publicity - but that's about the only (relatively small) downside we can think of.

It's not like 90-year-old Lee needs to up his cult credibility any further - the man has been in Star Wars movies, the Lord of the Rings trilogy, a James Bond film and he's frickin' Dracula. But how awesome would it be to have the imposing horror legend - with that big, booming voice of his - pop up on Doctor Who.

Horror icon David Warner (The Omen) has signed up to appear in a 2013 Who installment, so we'd argue that Lee is within the show's reach too. The main concern would probably be Lee's age and whether he could cop with the show's intense schedule, but then... Christopher Lee is no ordinary 90-year-old.

Clearly Dame Maggie is a legend at the box office but, as her recent Downton Abbey success proves, she's not 'above' doing television either. Unfortunately, we'd venture that it's that very success that could prohibit her from doing a stint on Doctor Who.

Downton is one of the jewels in ITV's crown - would they let one of the period drama's biggest draws appear in one of the BBC's own big-hitters? We'd guess not. Though we wouldn't want to be the ones to tell the Dowager Countess that she *can't* do something...

Alan RickmanAnother name that seemed to be doing the rounds a fair bit prior to the Grant reveal - perhaps Rickman's Harry Potter stardom has lent him some cult appeal?

In any case, the 66-year-old Brit is a fantastic actor and had a long list of incredible performances under his belt before Potter mania began. He'd be utterly brilliant on Doctor Who - but sadly, Rickman's TV appearances have been few and far between and we doubt he'd make an exception here.

Alright, so we're *mostly* joking about this one, but Her Majesty has cameoed in Doctor Who twice before, in 1988's 'Silver Nemesis' and 2007's 'Voyage of the Damned' - played both times by an actress, we hasten to add. Still, following her recent encounter with James Bond, maybe we shouldn't rule out the Real Queen for a guest spot. It'd make for a hell of a Christmas special...

Which big-name guest stars would you like to see in Doctor Who? Name your picks below!